Currently, speech input systems must be activated by the user shortly before the inputting of a relevant voice command. A so-called “Push-To-Talk” activation of this type is usually performed by a push-button on the steering wheel rim. The system must signal back to the user when it is ready to respond to his command, i.e., provide a readiness indication. It is conventional to realize this indication of readiness using a color change of an optical symbol on a display or using a short, one-time tone. Because in actual urban driving, the use of voice inputting is usually a secondary task, after the sate driving of the vehicle, and the driver is often subject to significant mental stress by the actual task of driving, he may overlook the optical symbol indicator on the display, it is possible for him not to hear the acoustical check-back signal, or he may forget that the check-back signal has already occurred. As a result, he is uncertain with regard to the condition of the system, which can lead to operating errors, faulty functioning, and consequently to a lack of acceptance by the user of a function control system that operates on the basis of voice input in a motor vehicle.